1. Field of the Invention
The present invention generally relates to magnetic disc drive apparatus and, more particularly, is directed to a magnetic disc drive apparatus suitable for use with, for example, a hard disc recording and reproducing apparatus.
2. Description of the Prior Art
A conventional magnetic disc (hard disc) drive apparatus will be explained hereinafter with reference to FIGS. 1 to 3.
A perspective view forming FIG. 1 shows an overall arrangement of a conventional magnetic disc drive apparatus. In FIG. 1, reference numeral 1 designates a casing of this magnetic disc drive apparatus and assembly parts and so on, which will be explained later, and which are accommodated within this casing 1. A magnetic disc rotating section 2 is a motor (i.e. outer rotor type motor) which rotates a magnetic disc (hard disc) 3.
There is shown a head arm 5 and a magnetic head 4 is mounted on the top thereof. This head arm 5 is rotated about a rotary shaft 6 provided at its opposite end portion by a voice coil motor (not shown).
A flexible printed circuit board 7 is accommodated within the casing 1, and this flexible printed circuit board 7 is operated as a transmission line which connects the magnetic head 4 mounted on the top of the head arm 5 with a recording/playback amplifier 8 mounted on a rigid printed circuit board 11 which will be described later. The above-mentioned assembly parts and so on are accommodated within the casing 1.
The rigid printed circuit board 11 is attached to the outside of the bottom of the casing 1. The recording/playback amplifier 8 is mounted on the rigid printed circuit board 11. As shown in a schematic block diagram forming FIG. 2, upon recording, a record signal from this recording/playback amplifier 8 is supplied through interconnected wires in the printed circuit board 7 to the magnetic head 4, and the record signal is recorded on a recording surface of the magnetic disc 3 (see FIG. 1) by the magnetic head 4. Upon reproduction, a recorded signal recorded on the magnetic disc 3 is reproduced by the magnetic head 4, and the reproduced signal is supplied through interconnected wires of the flexible printed circuit board 7 to the recording/playback amplifier 8.
A playback side frequency characteristic circuit (i.e. equalizer and/or filter) 9 is provided on the rigid printed circuit board 11 and this playback side frequency characteristic circuit 9 is adapted to waveform-equalize and/or filter-out the reproduced signal from the recording/playback amplifier 8.
A playback side pulse shaping circuit 10 is provided on the rigid printed circuit board 11, and this playback side pulse shaping circuit 10 is to pulse-shape the reproduced signal from the playback side frequency characteristic circuit 9 to thereby generate a digital signal (pulse signal). Such digital signal is fed to a reproduced signal processing system and so on which are not shown.
The upper portion of the above-mentioned casing 1 is covered with an upper lid (not shown) and this magnetic disc drive apparatus is incorporated into a computer or the like, wherein the recording and/or reproduction operation thereof can be controlled by a central processing unit (CPU), a controller or the like of the computer.
Another example of the conventional magnetic disc drive apparatus will be described with reference to FIG. 3, in which like parts corresponding to those of the conventional magnetic disc drive apparatus of FIG. 1 are marked with the same references and therefore need not be described in detail
In the example of the conventional magnetic disc drive apparatus, as shown in FIG. 3, the area of the flexible printed circuit board 7 accommodated within the casing 1 is increased, and also the recording/playback amplifier 8 is mounted on the flexible printed circuit board 7 unlike the magnetic disc drive apparatus of FIG. 1. According to this magnetic disc drive apparatus, the space of the rigid printed circuit board 11 can be increased by the amount corresponding to the recording/playback amplifier 8 and reproduced signal noise supplied to the circuits of the rigid printed circuit board 11 can be reduced.
In the conventional magnetic disc drive apparatus explained with reference to FIG. 1, the recording/playback amplifier 8, the playback side frequency characteristic circuit 9 and the playback side pulse shaping circuit 10 are mounted on the rigid printed circuit board 11, thus making it difficult to save the space of the rigid printed circuit board 11. Further, the recording/reproducing signals from the magnetic head 4 pass temporarily to the outside through the flexible printed circuit board 7. Further, an analog circuit and a digital circuit are mounted on the rigid printed circuit board 11 in a mixed fashion so that a noise is easily mixed into the recording/reproducing signals.
Since the conventional magnetic disc drive apparatus of FIG. 3 differs from the conventional magnetic disc drive apparatus of FIG. 1 only in that the recording/playback amplifier 8 is mounted on the flexible printed circuit board 7 accommodated within the casing 1, the space of the rigid printed circuit board 11 cannot be saved without difficulty. Also, there is then the substantial risk that the recording/reproducing signals will be deteriorated by inside or extraneous noise.